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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2837bbd63e7a32913c3f38fa300d8325dbd567d7e81a8ba0a642b8a28fbb8e4' 
  AND token = 'RCyll/ss32xj6LxYbZSHW2b0qoAEMSWhMA03i/SMD+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}